Advanceable roof prop arrangement



April 9, 1968 G. DOMMANN ADVANCEABLE ROOF' PROP ARRANGEMENT 3 SheeiS-Sheet L Filed Sept. 30, 1966 Fig. 2

n /NVENTOR GUNTHER unMMANN G. DOMMANN April 9, 196s ADVANCEABLE ROOF PROF ARRANGEMENT 5 Sheets-Sheet :2

Filed Sept. 30, 1966 /NVE/voR GUNTHER nuMMANN April 9, 196s G. DOMMANN 3,376,707

ADVANCEABLE ROF PROP ARRANGEMENT Filed Sept. 30, 1966 5 Sheets-Sheet Q U INVENTOR uNHEn nuMMANN United States Patent O ADVANCEABLE ROOF PROP ARRANGEMENT Gnther Dommann, Altlnnen, Westphalia, Germany, assignor to Gewerkschaft Eisenhutte Westphalia, Wethmar, near Lunen, Westphalia, Germany, a corporation of Germany Filed Sept. 30, 1966, Ser. No. 583,367

Claims priority, application Germany, Uct. 2, 1955,

11 Claims. (Cl. 61-45) The present invention relates to an advanceable roof prop arrangement, and more particularly a hydraulically energizable arrangement of suoh type including at least three prop means each coupled at the corresponding lower and upper portions thereof with a corresponding common lower beam and u-pper beam by means of respective lower and upper advancing means disposed on each prop means.

Roof prop arrangements are known which contain a pusher bar laterally situated at the forward portion theref of so as to make possible by displacing such pusher bar with respect to the prop means the forward advance of a mining conveyor in connection with longwall m-ining operations. In such operations, a conveyor is usually disposed longitudinally along a mine face, such -as a cool face, and a winning machine, such as a mining plow or mining planer, is displaced longitudinally back and forth along such conveyor in extractive engagement with the mine face so as to cause mineral being won to be guided onto the conveyor for removal from the site of operations. The conveyor must normally be urged in the forward direction of advance so that the mining machine used therewith may be kept in urging extractive engagement with the mine face. Understandably, as the work progresses, new layers of mineral will be exposed and it is necessary to advance the conveyor, usually in short steps, to maintain the proper positional relationship at the mine face. An attendant problem is the necessity for supporting the mine roof in the vicinity of the conveyor and planer alley, which is that area between the conveyor and the mine face itself along which the mining machine travels. Prop means, such as pit props, usually in the form of prop frames having a roof cap and floor skid between which one or more pit props are vertically positioned, are utilized to support the mine roof, and such .prop means are normally disposed on the side of the conveyor remote from the mine face. In order to provide support in the area over the conveyor and planer alley, the roof cap of such a prop frame, or the like, is often provided with a l preliminary cantilevered projection. Thus, by providing a pusher bar at the lower end of such prop means, and while the prop means are in pressure engagement with the roof and ii-oor, the conveyor may be urged in increments progressively toward the mine face as such new layers of mineral are exposed, without havin-g to release the prop means from supporting engagement with the roof and floor.

It wil-l be realized that each time the prop means is released from such pressure engagement with the mine roof and mine floor, the strata thereabo-ve are subjected to changes in pressure and counter-pressure with the everpresent danger of cave-in. Therefore, by using pusher bars to advance the conveyor, the prop means need only be released from pressure engagement with the roof and iloor at infrequent times whereby to advance the prop means to achieve a new amplitude of incremental extension orf the pusher bar for causing the conveyor in turn to execute in short steps the desired further advance thereof. Accordingly, the number of shifts in pressure on the roof is reduced and the roof is treated more gently than in operations carried out without a pusher bar of the type noted,

3,375,707 Fatented Apr. 9, i968 which of course is a serious consideration in the case of a brittle roof, i.e. one prone to cave-in.

It is also known to couple together a plurality of prop units, such as prop frames, directly to the conveyor and to combine together by means of a common support several prop units or frames to form a group. In such in stance, no advancing apparatus is necessary ttor the conveyor, but instead articulated bars are disposed on the groups of prop units or frames so as to interconnect the prop units at their forward portions. The junction points of such articulated or rotating bars are connected to the chain which drives the winning machine and are pulled forward in the direction of advance by the back and forth movement of the chain-driven winning machine, a control brought about by the tension or pressure in the .articulated bars, making in each instance one or ano-ther of t-he prop units a stationary point for causing the advance of the remaining prop unit or units with respect thereof.

In such prior -art apparatus, after the mineral has been stripped to expose a new layer and the beam or bar support coupling the plurality of prop units as a group has been advanced, such bar serves as a support for pulling forward the remaining prop units or frames which have yet to be advanced. If, for example, three prop units are connected to the beam, when the beam is advanced two such prop units are maintained under roof supporting pressure while the third prop unit or frame is retracted from such engagement so that it may be moved forward. If, however, the roof is b-rittle and caves in when such prop unit is loosened, the roof cap of the frame being advanced will usually become stuck against the roof, and as the -tloor skid is advanced, a bending force will be applied to the props in the frame or unit. The prop means will accordingly assume a rearwardly inclined position and the desired forward movement thereof under load becomes impossible.

It is an object of the present invention to overcome the foregoing drawbacks and to provide an advanceable roof prop arrangement having upper and lower guide beams.

It is another object of the present invention to provide an arrangement of the foregoing ty-pe including at least three prop means each coupled at the corresponding lower and upper portions thereof with a corresponding common lower beam and upper beam by means of respective lower and upper advancing means disposed on each prop means.

It is still another object of the present invention to provide an arrangement of the foregoing type which is durable in construction, simple and inexpensive to manufacture, and versatile in use.

It is a still further object of the present invention to provide an arrangement of the foregoing type which will permit non-adjacent prop means in a group of at least three prop means to be advanced while all such prop means remain under roof load, such that each prop means advanced will retain its proper attitude and position with respect to the other prop means and the mine roof and mine iloor, whereupon after being advanced each such prop means will be able to remain extended tensed rmly against the mine roof.

Other and further objects of the present invention will become apparent from a study of the within specificationand accompanying drawings, in which:

FIG. 1 is a schematic side elevation partially in section of a prop frame or unit having lower and upper beams in accordance with one embodiment of the present invention;

FIG. 2 is a schematic top view of an arrangement composed of -a group of three adjacent prop frames or units of the type shown in FIG. 1, illustrating in phantom certain details of construction;

FIG. 3 is a schematic side elevation partially in section D of an alternate embodiment of a prop frame or unit in accordance with the present invention;

FIG. 4 is a schematic top view showing an arrangement composed of three prop frames or units of the type shown in FIG. 3, with certain details of construction being shown in phantom;

FIG. 5 is a schematic side elevation view partially in section of a further embodiment in accordance with the present invention, and

FIG. 6 is a schematic top view of an arrangement of three prop frames or units of the type shown in FIG. 5 yet with the modification of a hinged or jointed top beam.

It has been found, in accordance with the present invention, that an advanceable hydraulic roof prop arrangement may be provided which comprises at least three individual laterally adjacent prop means each coupled at the corresponding lower portion thereof by a separate lower advancing means to a common lower beam independently disposed therealong and each coupled at the corresponding upper portion thereof by a separate upper advancing means to a common upper beam independently disposed therealong, each said advancing means being separately operable to displace linearly with respect to each other the particular prop means and the corresponding beam coupled thereby. Accordingly, upon first displacing linearly said beams with respect to all said prop means via said advancing means to advance said beams, then at most some of said at least three prop means may be displaced linearly via their corresponding lower and upper advancing means simultaneously so as to advance said at most some of said prop means while the remainder of said advancing means are held from operation and thus prevent linear displacement of the remainder of said at least three prop means with respect to said beams and thereafter said remainder of said at least three prop means may be displaced linearly via said remainder of the corresponding7 lower and upper advancing means simultaneously so as to advance said remainder of said at least three prop means while the corresponding lower and upper advancing means of the already advanced prop means are held from operation, with the prevention substantially of any tilting of said prop means during the advancement thereof even when said prop means are under load during such advancement.

Preferably, each such prop means is in the form of a prop frame having a oor skid and a roof supporting cap as well as at least two upright vertically extensible and retractable pit props interposed therebetween. Also, it is preferable that the upper beam be guidedly displaceable in each corresponding roof cap. Moreover, the advancing means may take the form of any linearly displaceable means capable of change in effective length, such as a piston-cylinder means which may be hydraulically or pneumatically controlled and/ or operated, whereby to achieve the relative displacement of the individual prop means and the lower and upper beams, as the case may be.

In accordance with one feature of the invention, the roof cap may be provided with a preliminary supporting cap connected thereto with a preliminary upwardly and outwardly inclined auxiliary piston-cylinder means extending from the lower portion of each prop frame to such preliminary cap to support the preliminary cap thereat. In the same way, a further feature lof the present invention contemplates the provision for a preliminary upwardly and outwardly auxiliary piston-cylinder means extending from the lower portion of each prop frame to the upper beam whereby to support such upper beam.

In accordance with an alternate feature of the present invention, the upper beam is composed of parallel subelements jointed to one another for articulation about corresponding parallel axes extending in the linear direction of advance. A further optional feature of the invention includes the positioning of lateral piston-cylinder means on each prop frame so as to extend operatively in a direction toward the next adjacent prop frame whereby to adjust the distance between the prop frames by impinging abutment against the adjacent portion of the next adjacent prop frame. Such lateral piston-cylinder means may be provided both on the roof cap and door skid on each prop frame to maintain proper lateral alignment of the frames with respect to each other.

Referring to the drawing, FIG. 1 shows a prop means in the form of a prop frame 1 having a pair of upright vertically extensible and retractable mining pit props 2 and 3 interposed between the overlying roof cap 4 and iioor skid 5'. The construction of prop means, such as frame 1, is well known and the prop means contemplated herein includes broadly any prop means which may consist of one or more individual props coupled together for simultaneous horizontal movement along the mine floor and preferably interposed between a roof cap and floor skid means capable of simultaneous movement with the pit prop or props, the role of such prop means being to support the mine roof to take the load thereof during mining operations.

Normally, a mining conveyor 6, which may be in the form of a conventional double chain scraper conveyor, is disposed longitudinally along a mine face, and prop means are situated on the side thereof remote from the mine face to support the roof. By utilizing a forward cantilever portion as part of the roof cap, the area over the conveyor may be protected, as shown in FIG. l. Also, in order to displace the conveyor 6 in the forward direction of advance which is transverse the longitudinal direction of the conveyor, mine face and mining machine (not shown) in its operating path, a conventional advancing means S, consisting of a cylinder 9 defined within the foot skid 5 of the prop means having displaceably received therein the piston 10 to which the piston rod 11 is connected, is utilized. At the outer end of the piston rod 11, a conveyor pusher bar or lower beam 7 is disposed, more or less at the level of the adjacent side wall of the conveyor 6. Preferably, the beam 7 is articulatedly connected at 12 to the piston rod 11 so as to accommodate unevenness in the mine iioor while pushing conveyor 6 in the forward direction of advance, In order to undertake the advance of conveyor 6, the prop frame 1 must be placed under load against the mine roof to prevent undesired rearward movement of frame 1 under the i counter-weight of the conveyor and the mineral contents disposed thereon.

In accordance with the present invention, there is additionally provided, at a point spaced vertically from the mine floor and the conveyor and particularly near the roof, such as within the roof cap 4, an additional upper advancing means 14, preferably in the form of a pistoncylinder means including a cylinder 15 defined within roof cap 4 in which is displaceably received the piston 15 carried on the piston rod 17. Advantageously, an upper beam 13 is disposed at the outer end of piston rod 17 so that upon operating the advancing means 14, the beam 13 may be extended in the forward direction, for example to a position as shown in phantom to the right of beam 13 in FIG. 1. Optionally, beam 13 may be connected to piston rod 17 via an articulated connection 18.

It will thus be realized upon a review of FIG. 2 that a gang or group of three prop means of the type shown in FIG. l may be provided to achieve the advantages of the present invention, such prop means being designated 1a, 1b and 1c, The ganged prop means are formed of prop frames of the type shown in FIG. 1, and it will be realized that more than three such prop means may be ganged together for the desired purposes. The reference numerals in the gang structure of FIG. 2 are the same as those for the individual prop means 1 of FIG. l since the arrangement of FIG. 2 contemplates the use of three prop frames of the type shown in FIG. 1. From FIG. `2 it can lbe seen that the upper beam 13, in accordance with the present invention, is attached to the upper end portions of the respective frames 1a, 1b and 1c via the appropriate advancing means 14 located in the respective roof caps 4 but shown only in frame 1n. Also, the lower beam 7 is attached via the corresponding lower advancing means S with the respective oor skids 5 of the three (or more) prop means ganged together.

Conveniently, an optional feature is provided in accordance with the present invention in order to maintain alignment of the three prop units 1a, 1b and 1c, such feature being in the form of the lower lateral pistoncylinder means 19 mounted within the appropriate floor skid S and the upper lateral piston-cylinder means 20 mounted in the appropriate roof cap 4. The piston-cylinder means 19 and Z0, as is clear from FIG. 2, direct their force laterally so as to impinge via the projecting lower piston rod 21 and projecting upper piston rod 22, as the case may be, against the adjacent portion of the next adjacent prop means.

Nevertheless, advantageously, in accordance with the present invention, the arrangement of ganged prop means, including at least three such prop means, e.g. 1a, 1b and 1c, is maintained with the roof caps under load in pressure engagement with the mine roof during the entire mining operation. This ensures that the mine roof will not be robbed of support or disturbed by alternate thrusts of pressure and release from pressure which would otherwise -be caused by the extension and retraction of the particular roof cap to enable the particular prop means to be advanced. Instead, by reason of the presence of the common upper beam 13 in conjunction with the common lower beam 7 and particular sequential and simultaneous advancing means operation, rst the beams 7 and 13 may be extended up to their full amplitude in terms of the linear displacement inherent in the advancing means S and 14, whereby the lower beam will eiect the operative urgence forward in the direction of advance of the conveyor 6 thereat while the upper beam will guide along the mine roof therebefore in the vicinity of the mine face thereat. As the artisan will appreciate, known sensing means or detecting means, hydraulic or electrical in nature, may be employed to determine the amplitude of displacement of the advancing means 14 to permit the upper beam 13 to just engage the mine face thereat (see the article regarding the automation of roof supports in longwall mining for the prevention of roof breakouts by O. Jacobi, Essen, Germany, in Glckauf, vol. 101, No. 14, July 7, 1965).

In conjunction with the foregoing, it will be realized, in accordance with the present invention, that after the conveyor 6 has been urged by the lower beam 7 a given distance and while both the lower beam 7 and upper beam 13 are more or less fully advanced, then one prop means or two non-adjacent prop means in the ganged group of three or more prop means may be advanced by reverse actuation of the lower and upper advancing means thereof attached to the beams 7 and 13, while under load, without adverse er'fect on the mine roof, so long as the remaining prop unit or pair of non-adjacent prop units in the group are maintained more or less in their original position under load. The foregoing can be accomplished by energizing in reverse direction the upper and lower advancing means 8 and 14, for example, of the prop unit 1b so that such prop unit will advance up to the now advanced beams 7 and 13, after which the non-adjacent prop units 1a and 1c may be advanced by reverse actuation of their lower and upper advancing means 8 and 14 to bring the same closely adjacent not only the previously advanced prop unit 1b but also the comm-on lower beam 7 and common upper beam 13. In this manner, while all props remain under load during the advance of the beams and successively of the at least three prop means in the gang group, the roof is maintained under constant supporting pressure without adverse disturbances thereof, the conveyor 6 is advanced in the desired manner, and the individual prop means of the group are advanced safely in non-adjacent successive order. To accomplish the foregoing, conventional valve control means are employed for energizing the advancing means 8 and 14 so that after the simultaneous energizing of all of the advancing means 14 and after the simultaneous energizing of all the advancing means 8 whereby to extend the beams 13 and 7, those non-adjacent advancing means 14 and 7 indigenous to the non-adjacent prop units to lbe rst advanced under load may be energized in reverse manner to cause such non-adjacent prop units to be advanced up to the point of advance of the already advanced 'beams 13 and 7. During such time, the advancing means 8 and 14 of the remaining prop units will be held against operation to maintain in original position such remaining prop units. These remaining prop units serve as the point of leverage for achieving under load the advance of the aforementioned non-adjacent prop units. Once the rst advance has been achieved of such non-adjacent prop units, then the advancing means 14 and 7 of the already advanced prop units will be held against operation and the same procedure applied with respect to the remaining not yet advanced nonadjacent prop means. Specifically, the advancing means 14 and 7 of such remaining prop means will be energized to cause the forward pull under roof load of the not yet advanced prop unit or units while the advancing means 14 and 7 of the already advanced prop units will be held against operation.

Signiiicantly, by reason of the presence of the lower and upper beams and by the forward, reverse or fixed position control of the advancing means in question, one or more of the prop units may be advanced under load and without disturbing the disposition of the mine roof thereabove because of the common connection of the prop units being advanced and those not ybeing advanced with the upper and lower beams.

It will be realized that the present arrangement of ganged prop units or frames will permit via the optional feature of articulated connections 12 and 18 of Ibeams 7 and 13 to the appropriate piston rods 11 and 17, respectively, the shifting of the arrangement to a direction at an angle to the previous longitudinal direction of advance or alignment of a given prop unit or units to return to a previous longitudinal attitude or to achieve a new attitude, depending upon the conditions met in the mineway. Versatility of operation is thereby attained, so that mobility and control of direction of advance may be enjoyed with a minimum of surveillance and attendance by the workmen.

It will be appreciated by the artisan that the instant cycle of operation of rst advancing the beams to full amplitude under the mining conditions, then advancing at most some of the non-adjacent prop units or frames in the arrangement, and thereafter advancing the remainder of such prop units or frames, while all prop means are under roof load, lends itself to automatic control by the simple use of hydraulic, electrical or timed steering mechanisrns, with suitable sensing and/or detecting devices, for automated mining operations. A master hydraulic control valve may be employed for this purpose, with manual overtake, if desired, such that in a first step the lower and upper advancing means 7 and 14 are energized simultaneously to displace in the forward direction the beams 7 and 13, then in a second step the lower and upper advancing means of selected non-adjacent prop units in the gang arrangement are energized in reverse direction to pull forwardly under roof load such non-adjacent prop units up to the point of advance of the beams 7 and 13, and thereafter in a third step the lower and upper advancing means of the remaining prop unit or units in the gang arrangement are energized in said reverse direction to pull forwardly under roof load such remaining prop unit or units up to said point of advance of the -beams 7 and 13. Of course, lwhen the lirst selected advancing means 8 and 14 are reverse energized, the advancing means 8 and 14 of the remaining prop unit or units will be held against operation or displacement, and when the remaining prop unit or units are advanced by reverse energizing of their advancing means S and 14, the previously reverse ener* gized advancing means of the already' advanced nonadjacent prop unit or units will be held against operation or displacement. To accomplish these steps, the control means may assume the form of valve means movable in a cycle to a first position at which all advancing means 8 and 14 are energized by the flow of hydraulic or pneumatic pressure medium in the forward direction to advance the beams with respect to the gang of prop units, thence to a second position at which the advancing means of the non-adjacent selected prop units will be reverse energized by such pressure medium vwhile the non-selected remaining upper and lower advancing means will be closed of from pressure medium flow to x their position, and thence to a third position at which the advancing means of the non-selected remaining prop units will be reverse energized by such pressure medium while the already selected upper and lower advancing means will be closed olf from pressure medium ow to tix their position. The form that such valve control means will take can be selected at random by the artisan, or manual control of the pressure uid medium to the upper and lower advancing means may be utilized so as to achieve the sequential advancement of non-adjacent prop units in the gang arrangeent under roof load for the desired proposes (ci. said Glckauf article).

As may be seen from FIGS. 3 and 4, an alternate em- -bodiment of the invention is provided, including as the prop means, units such as the prop frame 23 having three sets of props 24, 25 and 26 interposed vertically between the roof cap composed of members 27, 28 and 29 articulatedly interconnected at joints 30 and 31 and the oor skid 35, with the auxiliary upwardly and outwardly incined prop 32 pivotally connected at joint 33 to the forwardmost cap member 29 at its upper end and pivotally connected at joint 34 to the foot skid 35 at its lower end. The props 24, 25, 26 and 32 are extensible and retractable in the same manner as props 2 and 3 of FiG. l. In this embodiment as well, a lower beam 36 is connected to the outer end of the piston rod of advancing means 37 shown in the form of a piston-cylinder arrangement, while upper beam 39 is connected to the outer end of the piston rod of advancing means 40 also shown in the form of a pistoncylinder arrangement. In this embodiment, rearward p0rtions 41 on upper beam 39 extend within grooves 42 dened on the upper side of the forward cap 29 to guide the beam 39 in its back and forth movement in longitudinal direction during the operation of the advancing means 4i).

Also, lower lateral piston-cylinder means 43 and upper l lateral pistoncylinder means 44 ywhich include the laterally projecting lower piston rod 45 and upper piston rod 46, respectively, may be used advantageously for impinging against the surface of the next adjacent prop means in order to maintain alignment of the prop units with respect to one another.

It will be realized from FIG. 4 that in fact each prop frame 23, shown in the form of the ganged prop frames 23a, 23!) and 23C, include a pair of rear props 24, a pair of intermediate props 25 and a pair of forward Props 26, with a single inclined prop 32, so as to achieve greater roof supporting ability, with the lower advancing means 37 being conveniently disposed axially between the intermediate and forward prop pairs 25 and 26, respectively. From FIG. 4, the rearwardly extending portions 41 disposed displaceably within grooves 42 may be appreciated, whereby the weight of the upper beam 39 is readily distributed while the path of movement of such upper 'beam is closely guided.

The operation of the arrangement of FIGS. 3 and 4 is the same as that of the arrangement shown in FIGS. l and 2 since lower and upper beams 36 and 39 and lower and upper advancing means 37 and 40 are counterpart elements to lower and upper beams 7 and 13 and lower and upper advancing means 3 and 14, respectively.

it will be realized that optional articulated connections, such as connection 38 between beam 36 and advancing means 37, may be provided in the same manner as in the embodiment of FIGS. l and 2, and if desired similar articulated connections (not shown) may be utilized be tween the upper beam 39 and the appropriate piston rod of the advancing means 4t) similar to the manner shown for the upper beam 13 at 18 in FIG. l.

In FIG. 5 a similar prop frame 50 is shown having upwardly extending pit props 51 and 52 situated between the door skid 53 and the roof cap 54, with such props being extensible and retractable in the usual manner to achieve the desired support of the roof. In the same way, a lower beam 55 is shown connected to a lower advancing means 56 while an upper beam 58 is shown connected to an upper advancing means 59. Analogous to the construction of FIG. 3, an upwardly and outwardly inclined prop or piston-cylinder means 62 is provided, which iS connected by the articulated connection 63 to the upper beam 5S and to the door skid 53 by the articulated connection 64. To achieve purposeful operation, the piston rod of the upper advancing means 59 is similarly connected via the articulated connection to the upper beam 53 while the lower beam 55 may also be articulatedly connected optionally via connection 57 to the piston rod of the lower advancing means 56. To achieve proper guidance of the somewhat larger beam 58 in this embodiment, guide elements 61 may be provided at the rearward portion of the beam `58 extending into an appro-` priate guide opening 61a shown in phantom in cap 54.

The embodiment of FIG. 6 is similar to that of FIG. 5 and includes three prop units of the type shown in FIG. 5, designated prop units 50a, SGb and 50c. It will be seen that the frame 5G of FIG. 5 may be provided with a pair of rear props 51 and front props 52 and with separate roof caps 54 at the underside of which the upper advancing means 59 may be disposed with a common oor skid 53 therebelow.

The operation of the and in FIG. 6 will be the same as that noted above in connnection with the embodiment of FIGS. 1 and 2. Nevertheless, because of the presence of the auxiliary piston-cylinder means 62,k such piston-cylinder means will be energized in conjunction with the energizing of the upper advancing means 59 so that the normal longitudinal path of displacement of upper beam 5S will be maintained. This is somewhat assured by the presence of guide elements 6l in conjunction with guide opening 61a.

In particular, in FIG. 6 an alternate arrangement of upper beam 58 as shown in FIG. 5 is provided. In this embodiment the upper beam is designated 58' to illustrate that such beam is composed of a number of subelements 65 which are articulatedly jointed via the joints or hinged connections 66 lateraly therebetween. In this manner, the beam 58' may accommodate variations in` the horizontal disposition of the arrangement which may be caused by unevenness in the mine iloor or mine roof, yet without deviation of the sub-elements 65 with respect to one another, except articulation about the parallel axes of the laterally spaced apart joints 66 having axes of pivot extending in the longitudinal direction and preferably in the same vertical plane as that of the operating axes of the corresponding upper advancing means 59.

Thus, in accordance with the present invention, an upper beam is provided in the previous ganged arrangement of prop means which forms an advanceable portion of a preliminary roof cap (e.g., FIGS. 3 and 4) or an advanceable preliminary roof cap itself (eg, FIGS. l and 2 and/ or FIGS. 5 and 6). It is advantageous to provide the upper beam at the particular roof cap in question via the advancing means utilized. Indeed, in order to avoid in the advancement of the over-all ganged arrangement all orccs which might produce a tilting of the prop units or of the props in each individual frame i arrangement shown in FIG. 5

being advanced, it is advisable to dispose lateral pistoncylinder means between adjacent prop means. The individual prop frames in the ganged arrangement may be properly advanced both at the floor and at the roof in accordance with the present invention, considering adverse mining conditions, faults, uneveness in the mine floor and mine ceiling caused during mining operations, etc., whereby, after closing oif the advancing means or advancing cylinders from vdisplacement except for the one or more prop units to be advanced, to advance such unit or units forwardly under partial load by using the upper and lower advancing means for this purpose. Advantageously, in accordance with the present invention, therefore, the retraction of the props of the prop units being advanced is no longer necessary, and by using the upper and/or lower beams in accordance with the present invention, it is also possible to bring about corrections in the direction of movement whenever a particular prop unit is brought into a more or less skewed or oblique position by variation of the operative length of advancing means or advancing cylinders.

The use of t-he upwardly and outwardly directed auxiliary prop means provides the advantage of holding securely against the roof wide supports of the upper beams which constitute large area preliminary roof supporting caps (FIG. 3) in addition to being usable against the upper beam for the purpose of advancing non-adjacent prop units while under roof load (FIG. 5).

As the artisan will appreciate, in addition to the provision for jointed or hinged sub-elements for the beam as shown in FIG. 6, it is also possible to provide such beam in the form of a yieldingly elastic material, such as spring steel. The use of spring steel will similarly achieve adaptation to irregularities in the mine roof as will occur with the hinged sub-element construction shown in FIG. 6.

It will be realized further by the artisan that the upper beam of the present invention can also be constructed as a mining machine guide so as to accommodate thereat an upper mining machine, such as a planer. In this connection, the upper beam may in fact carry such upper mining machine for back and forth movement therealong or merely guide such mining machine thereat to achieve the constant urgence of the mining machine in extractive engagement with the upper portion of the mine face. Moreover, where a mining machine of extraordinary height is utilized, it is often necessary to provide for the guidance thereof at the upper portion of such mining machine, such as a planer, and thus guidance may be attained via the upper beam of the present invention.

It will be realized that the various props and/or advancing means and/or piston-cylinder means may be hydraulically or pneumatically operated, utilizing suitable pressure medium for this purpose. Furthermore, it will be realized that the .term advancing means as used herein is meant to embrace not only a specific doubleacting piston-cylinder means but also generally any equipment which will perform a mechanical change in effective length between two points of structural connection. The term prop means as used herein contemplates broadly any means for supporting a mine roof or the like, preferably disposed between a floor skid and roof cap, such prop means including one or more individual pit props or the like. While it has been indicated herein that the lower and upper beams are connected to the floor skid and the roof cap via the upper and lower advancing means, such as piston-cylinder means, it will be realized that such connections between the upper and lower beams and the particular props in question may be located at any points on the prop means in the same general longitudinal direction, so long as such points are vertically spaced apart whereby to achieve upper and lower spaced disposition of the beams for the purposes in question. Indeed, the lower beam will in any event be distinct from a mining conveyor situated at l i) the mine floor and will not be considered connected thereto but rather abuttable there-with for the purpose of pushing in a forward direction the conveyor for the desired advancement.

It will be appreciated, for example in connection with the operation of the ganged arrangement of FIGS. l and 2, that without the presence of the pair of upper and lower beams in accordance `with the present invention, any attempt to advance a given prop frame under load would cause the rearward tilting of the prop frame due to the frictional pressure and obstructions which the roof cap would undoubtedly encounter in the longitudinal direction of advance. It will be realized that as the mineral is won from the mine face, in the vicinity of the mine floor during normal longwall mining operations, portions of the overhanging mineral, for example roof coal, will break away and fall onto the conveyor and/or into the mining machine alley between the conveyor and mine face, leaving uneven lroof areas still containing mineral to be extra-cted. By reason of the upper beam, in accordance with the present invention, not only will the frames be able to be advanced successively under roof load, i.e. without having to retract the individual prop frames for advance and thereafter extend the same into pressure engagement with the roof once more, but also such upper beam will serve to thrust forward any overhanging mineral to clear a path for the prop frames in the ganged arrangement to be next advanced. Additionally, the upper beam will serve as a preliminary roof support in the precarious, otherwise unsupported, roof area overlying the conveyor and mining machine alley. Indeed, as the upper beam probes forward during its advance with respect to the ganged arrangement, detecting means used in connection therewith may determine the counterforce met thereby so as to avoid damage to the equipment and/ or to permit manual adjustment of the positional attitude of the particular frame or yganged arrangement so as to odset such counterforces. Since the individual prop frames will only be advanced under roof pressure after the upper beam has already been advanced, the path of movement thereof in the immediate area of the mine roof will be suciently clear to permit the advance to take place of the prop frames in the desired ordinal sequence without hindrance and without experiencing the prior art difficulties of rearward tilting of the cap and/ or props.

A most important advantage of utilizing the instant construction whereby the individual prop elements may be advanced while under roof load, is the fact that no disturbances of the roof will occur as would otherwise be the case in frequent extension and retraction of prop frames. Such extensions and retractions can understandably cause changes in pressure on the roof and dangerous changes in the condition of the roof strata. This is especially true with regard to delicate or brittle roofs, such as those which contain draw slate.

As aforesaid, by particular control of the increment of advance actuation or reverse actuation of a given advancing means, such as a piston-cylinder means, a transversely misaligned prop frame may be returned to the proper positional relationship with the remaining prop frames of the group, or all of the prop frames may be influenced in their transverse disposition with respect to one another by appropriate variation in the actuation of the advancing means, for example to change the longitudinal direction of advance of the ganged arrangement for one purpose or another. Indeed, pivoting of the arrangement about a given point is thus possible where it is desired to follow a new direction of mine face operation. In the same way, by the appropriate variation in the actuation of the lateral piston-cylinder means, the longitudinal disposition of one prop frame with respect to the next may be changed for the same purpose as noted immediately hereinabove or for the purpose of accommodating unevenness in the mine floor and/or mine ceiling and/or :for negotiating travel in the longitudinal direction in closer or farther apart adjacent disposition of the prop frames with respect to one another. Advantageously, the lateral piston-cylinder means will siidingly engage the appropriate side surface of the next adjacent roof cap and/ or oor skid so that the particular side-by-side positional attitude of the adjacent frames in question may be maintained even when one such frame is fixed from movement while the other such frame is advanced.

it will be realized in connection with the embodiment of FIGS. 3 and 4, for example, that the upper beam may be connected to the particular roof cap via the advancement means such that by reason of appropriate articulations, such upper beam can be shifted at an angle to the normal position for direction-correcting purposes and allowance is made for this purpose by providing the grooves on the upper side of the forwardrnost cap member of slightly greater width than the width of the corresponding rearward portion of the upper beam guided thereat. Such articulations may be executed in the same manner as in connection with the articulations permitted by the analogous connections between the upper beams and advancing means of the embodiments of FIGS. 1-2 and 5-6, as the case may be.

Furthermore, by use of a particular arrangement of FGS. 3-4 and/or FGS. 5-6, a broad preliminary support of the mine roof newly exposed may be attained prior to the advance of the main prop support provided by the prop frames in question. The preliminary support is aided by the presence of the upwardly and outwardly inclined prop i.e. or piston-cylinder means, yet it will be realized that the main support will still be provided by the prop frames in the ganged arrangement. The important factor is to provide as close to the mine face as possible as soon as the mineral has been extracted therefrom, a preliminary support to minimize the tendency of the roof area thereat to cave-in prior to the next advance of the main prop frame thereat.

It will be obvious to the artisan that the reason for advancing the prop `frames in the ganged arrangement in successive steps and in advancing non-adjacent prop frames in any step is to avoid excessive disturbance of the roof while providing as Vfar as possible unchanged roof load support via the arrangement.

As aforesaid, a detector, mechanical, pneumatic or electrical, may be disposed on the upper beam near the roof to control the operation of the advancing means for the further advancement of the upper beam and/ or the lower beam and/ or for the successive advancement of the non-adjacent prop frames to be advanced, in accordance with the degree of excursion of the upper beam from the prop frame arrangement toward the mine face. Thus, the construction and arrangement provided by the present invention permit ready adaptability to automatic control and operation without the need for surveillance of lthe mine workmen and with the minimizing of the number of workmen actually needed.

Therefore, in accordance with the present invention, an advanceable roof prop arrangement is provided which comprises at least three laterally spaced apart upright roof prop means each coupled in a longitudinal direction at the corresponding lower portion thereof by a separate and independently operable lower piston-cylinder means to a common lower beam independently disposed in a transverse direction along said at least three prop means and each coupled in said longitudinal direction at the corresponding upper portion thereof by a separate and independently operable upper piston-cylinder means to a common upper beam independently disposed in said transverse direction therealong, each said piston-cylinder means being independently operable to displace toward and away from each other in said longitudinal direction the particular prop means and the corresponding beam coupled thereby, whereby upon first operating all said piston-cylinder means to displace said beams 'in said longitudinal direction away from all said prop means l2 then at most some of said at least three prop means may be displaced in said longitudinal direction by operating the corresponding lower andtupper piston-cylinder means thereof simultaneously so as to advance in said direction said at most some prop means with respect to the remainder of said prop means while the corresponding remainder of said lower and upper piston-cylinder means` are held from operation and thus prevent displacement of said remainder of said prop means with respect to said beams and thereafter said remainder of said prop means may be displaced in said longitudinal direction by operating said corresponding remainder of said lower and upper piston-cylinder means simultaneously so as to advance in said direction said remainder of said prop means while the corresponding lower and upper piston-cylinder means of the already advanced prop means are held from i operation and thus prevent displacement of said already advanced prop means With respect to said beams, with the attendant prevention substantially of any tilting of said prop means during the advancement thereof even lwhen said prop means are under roof load during such advancement.

More particularly, such arrangement comprises three transversely spaced apart longitudinally extending prop frames capable of changing their effective roof supporting height, a common lower beam and a common upper beam each independently disposed transversely along the adjacent longitudinal ends of all three said frames at the` corresponding lower and upper end portions of said frames, and separate and independently operable corresponding lower and upper piston-cylinder meansA of changeable effective length connecting operably each frame both at the lower and upper portions thereof with the corresponding beam.

It wiil be appreciated that the instant specification and drawings rare set forth by way of illustration and not limitation, and that various modifications and changes may be made without departing from the spirit and scope of the present invention which is to be limited only by the scope of the appended claims.

What is claimed is:

1. Advanceable hydraulic roof prop arrangement which comprises at least three individual laterally adjacent prop means each coupled at the corresponding lower portion thereof by a separate lower advancing means to a cornmon lower beam independently disposed therealong and t each coupled at the corresponding upper portion thereof by a separate upper advancing means to a common upper beam independently disposed therealong, each said advancing means being separately operable to displace linearly with respect to each other the particular prop means and the corresponding beam coupled thereby, whereby upon rst displacing linearly said beams with respect to all said prop means via said advancing means to advance said beams then at most some of said at least three prop means may be displaced linearly via their corresponding lower and upper advancing means simultaneously so as to advance said at most some of said prop means while the remainder of said advancing means are held from operation and thus prevent linear displacement of the remainder of said at least three prop means with respect to said beams and thereafter said remainder of said at least three prop means may be displaced linearly via said remainder of the corresponding lower and upper advancing means simultaneously so as to advance said remainder of said at least three prop means while the corresponding lower and upper advancing means of t-he already advanced prop means are held from operation, with the prevention substantially of any tilting of said prop means during the advancement thereof evenwhen said prop means are under load during such advancement.

2. Arrangement according to claim 1 wherein each of said prop means is in the form of a prop frame having a door skid and a roof supporting cap and said upper beam is guided displaceably in each corresponding roof cap, and wherein said advancing means include advancing piston-cylinder means.

3. Arrangement according to claim 2 wherein each said roof cap is provided with a preliminary supporting cap connected thereto and a preliminary upwardly and outwardly inclined auxiliary piston-cylinder means extends from the lower portion of each said prop frame to said preliminary cap to support said preliminary cap.

4. Arrangement according to claim 2 wherein a preliminary upwardly and outwardly inclined auxiliary piston-cylinder means extends from the lower portion of each said prop frame to said upper beam to support said upper beam.

5. Arrangement according to claim 2 wherein said upper beam is composed of parallel sub-elements jointed to one another for articulation about corresponding parallel axes extending in the linear direction of advance.

6. Arrangement according to claim 2 wherein lateral piston-cylinder means are provided on each said prop frame extending operatively in a direction toward the next adjacent prop frame to adjust the distance between said prop yframes by impinging abutment against the adjacent portion of the next adjacent prop frame.

7. Arrangement according to claim 6 wherein separate lateral .piston-cylinder means are provided both on said roof cap and said floor skid of each prop frame to maintain proper lateral alignment of said prop frames with respect to each other.

8. Arrangement according to claim 1 which comprises at least three laterally spaced apart upright roof prop means each coupled in a longitudinal direction at the corresponding lower portion thereof by a separate and independently operable lower piston-cylinder means to a common lower *beam independently disposed in a transverse direction along said at least three prop means and each coupled in said longitudinal direction at the corresponding upper portion thereof by a separate and independently operable upper piston-cylinder means to a common upper beam independently disposed in said transverse direction therealong, each said piston-cylinder means being independently operable to displace toward and away `from each other in said longitudinal direction the particular prop means and the corresponding beam coupled thereby, whereby upon first operating all said piston-cylinder means to displace said beams in said longitudinal direction away from all said prop means then at rnost some `of said at least three prop means may be displaced in said longitudinal direction by operating the corresponding lower and upper piston-cylinder means thereof simultaneously so as to advance in said direction said at most some prop means with respect to the remainder of said prop means while the corresponding remainder of said lower and upper piston-cylinder means are held from operation and thus prevent displacement of said remainder of said prop means with respect to said beams and thereafter said remainder of said prop means may be displaced in said longitudinal direction by operating said corresponding remainder of said lower and upper piston-cylinder means simultaneously so as to advance in said direction said remainder of said prop means while the corresponding lower and upper piston-cylinder means of the already advanced prop means are held from operation and thus prevent displacement of said already advanced prop means with respect to said beams, with the attendant prevention substantially of any tilting of said prop means during the advancement thereof even when said prop means are under roof load during such advancement.

9. Arrangement according to claim 8 wherein each said Iprop means is in the form of a longitudinally extending prop frame having a iloor skid and a roof supporting cap as well as at least two upright vertically extensible and retractable pit props interposed therebetween.

10. Arrangement according to claim 9 wherein said upper beam is guided displaceably in each corresponding roof cap.

11. Advanceable hydraulic roof prop arrangement according to claim 1 which comprises three transversely spaced apart longitudinally extending prop frames capable of changing their eectiveroof supporting height, a common lower beam and a common upper beam each independently disposed transversely along the adjacent longitudinal ends of all three said frames at the corresponding lower and upper end portions of said frames, and separate and independently operable corresponding lower and upper piston-cylinder means of changeable effective length connecting operably each frame both at the lower and upper portions thereof with the corresponding beam to achieve under roof load on said frames the extension in said longitudinal direction of said beams from said frames by operating all said piston-cylinder means together to increase their effective length and thereafter the advance in said longitudinal direction of at most two non-adjacent frames of said three frames by reverse operation of the corresponding piston-cylinder means therefor to decrease their efrective length while holding the remaining piston-cylinder means from changing their effective length and in turn the remaining at least one frame from advance, and finally the advance in said longitudinal `direction of said remaining at least one frame by such reverse operation of the corresponding remainder of said piston-cylinder means therefor while holding the piston-cylinder means of such already advanced at most two frames from changing the etective length thereof.

References Cited FOREIGN PATENTS 1,195,253 6/1965 Germany.

JACOB SHAPIRO, Primary Examiner. 

1. ADVANCEABLE HYDRAULIC ROOF PROP ARRANGEMENT WHICH COMPRISES AT LEAST THREE INDIVIDUAL LATERALLY ADJACENT PROP MEANS EACH COUPLED AT THE CORRESPONDING LOWER PORTION THEREOF BY A SEPARATE LOWER ADVANCING MEANS TO A COMMON LOWER BEAM INDEPENDENTLY DISPOSED THEREALONG AND EACH COUPLED AT THE CORRESPONDING UPPER PORTION THEREOF BY A SEPARATE UPPER ADVANCING MEANS TO A COMMON UPPER BEAM INDEPENDENTLY DISPOSED THEREALONG, EACH SAID ADVANCING MEANS BEING SEPARATELY OPERABLE TO DISPLACE LINEARLY WITH RESPECT TO EACH OTHER THE PARTICULAR PROP MEANS AND THE CORRESPONDING BEAM COUPLED THEREBY, WHEREBY UPON FIRST DISPLACING LINEARLY SAID BEAMS WITH RESPECT TO ALL SAID PROP MEANS VIA SAID ADVANCING MEANS TO ADVANCE SAID BEAMS THEN AT MOST SOME OF SAID AT LEAST THREE PROP MEANS MAY BE DISPLACED LINEARLY VIA THEIR CORRESPONDING LOWER AND UPPER ADVANCING MEANS SIMULTANEOUSLY SO AS TO ADVANCE SAID AT MOST SOME OF SAID PROP MEANS WHILE THE REMAINDER OF SAID ADVANCING MEANS ARE HELD FROM OPERATION AND THUS PREVENT LINEAR DISPLACEMENT OF THE REMAINDER OF SAID AT LEAST THREE PROP MEANS WITH RESPECT TO SAID BEAMS AND THEREAFTER SAID REMAINDER OF SAID AT LEAST THREE PROP MEANS MAY BE DISPLACED LINEARLY VIA SAID REMAINDER OF THE CORRESPONDING LOWER AND UPPER ADVANCING MEANS SIMULTANEOUSLY SO AS TO ADVANCE SAID REMAINDER OF SAID AT LEAST THREE PROP MEANS WHILE THE CORRESPONDING LOWER AND UPPER ADVANCING MEANS OF THE ALREADY ADVANCED PROP MEANS ARE HELD FROM OPERATION, WITH THE PREVENTION SUBSTANTIALLY OF ANY TILTING OF SAID PROP MEANS DURING THE ADVANCEMENT THEREOF EVEN WHEN SAID PROP MEANS ARE UNDER LOAD DURING SUCH ADVANCEMENT. 